The ensuing detailed description generally relates to a method for joining inner and outer tubes with fins therebetween so that a heat exchanger tube is provided with benefits in the manufacturing process not contemplated by the prior art.
The following patents appear to be relevant to the patent process and are the closest art of which applicant is aware.
U.S. Pat. No. 2,778,610, Brueggar PA1 U.S. Pat. No. 3,578,075, Winter PA1 U.S. Pat. No. 3,730,229, D'Onofrio PA1 U.S. Pat. No. 3,887,004, Beck PA1 U.S. Pat. No. 4,031,602, Cunningham et al.
Cunningham et al discloses a method of making a heat transfer tube wherein a finned central core is inserted within the interior of an outer tube which is then subjected to an external finning operation to mechanically bond the parts together and to provide fins on the outer surface of the outer tube. The Bruegger patent discloses a method of making a fin tubing in which fins are disposed within grooves formed in an inner tube and compression bands or rings are disposed around the outer edges of the fins and compressed to retain the parts in the assembled condition.
Beck discloses a heat exchanger wherein a finned inner tube having fins of novel cross-sectional configuration are encircled within a tubular shell 38.
The D'Onofrio patent discloses a heat exchanger tube and method for making such a tube wherein an inner tube having external helical fins is disposed within the interior of an outer tube in coaxial reltionship therewith and a finned third tube disposed around the cylindrical outer tube to form a unitary structure. The Winter patent is of general interest in that it shows the forming of a metal tube with spirally wound corrugations for use in a heat exchanger.
By way of contrast, the instant application specifies and is directed to a method for making heat exchanger tubes in which the inner and outer tubes are brought into frictional engagement by the interposing therein of fins having various geometrical configurations and in which the inner tube is expanded outwardly to provide the frictional engagement.